Changing Weather Patterns Impact Nitrogen Management

Iowa State University climatologist Elwynn Taylor believes we are entering a 25-year period of greater volatility of both weather and corn yields.

Published on: Feb 6, 2014

From flood to drought, the nation's breadbasket has had to contend with great weather extremes in recent years. In general, the Midwest is experiencing a period of warmer winters, higher minimum temperatures, higher dew points, greater moisture variability and more intense weather events, according to climatologists studying weather trends.

For example, North Dakota's growing season has lengthened by 12 days since 1879 and Iowa has 50% more days with measurable precipitation now than it did in the 1900s. This past year, Iowa began the season with widespread drought followed by the wettest spring in 140 years of recordkeeping and a droughty summer. This is the third year that science faculty and research staff from Iowa's universities and colleges signed a statement warning that climate change has profoundly disrupted ag production and is projected to be more harmful in coming decades.

Peter Scharf, nutrient management specialist at the University of Missouri, estimates that 2 billion bushels of corn were lost due to nitrogen deficiency in corn from 2008 to 2011, when there was widespread, excessive rainfall in the Midwest.
Peter Scharf, nutrient management specialist at the University of Missouri, estimates that 2 billion bushels of corn were lost due to nitrogen deficiency in corn from 2008 to 2011, when there was widespread, excessive rainfall in the Midwest.

Looking at long-term trends, Elwynn Taylor, Iowa State University climatologist, believes we are entering a 25-year period of greater volatility of both weather and corn yields. "Our climate goes through wet, dry, hot and cold cycles of about 40 years," Taylor says. "Since 1865, there has been a trend of 18 years with fairly consistent weather and corn yields in the Corn Belt followed by 25 years of highly variable weather and corn yields. This cycle has been repeated four times. It appears that 2012 was year one of the next 25 years of extremes."

While there may be debate about the cause of climate change, there is no doubt that farmers will need to adapt to changing weather patterns that affect growing seasons, crop diseases and pests, water availability and nutrient management. "Climate is changing in our own backyards, and it's changing at a pace that is startling," says Mark Seeley, University of Minnesota climatologist. "We are seeing profound consequences already. The need to adapt is very much present."

Strategies to protect nitrogen
Nitrogen is a key crop nutrient that is significantly affected by weather. With increased annual precipitation, more heavy rainfall events, higher temperatures and increased humidity, there is greater chance of losing nitrogen from leaching, volatilization and denitrification.

Peter Scharf, nutrient management specialist at the University of Missouri, estimates that 2 billion bushels of corn were lost due to nitrogen deficiency in corn from 2008 to 2011, when there was widespread, excessive rainfall in the Midwest. The land area in the Midwest with 16 inches or more of rainfall in the spring (April – June) has dramatically increased in the last 25 years from less than 80,000 square miles to nearly 200,000 square miles in 2013. Drew Lerner, senior agricultural meteorologist and president of World Weather, Inc., forecasts another wet and cold spring for the eastern half of the country in 2014.